It is challenging to create artificial enzymes that mimic the outstanding catalytic efficiency and specificity of their natural analogs, while being more robust and easily prepared and applied. Amongst numerous approaches used to create robust enzyme mimics, the application of gold nanoparticles decorated with a dense monolayer of peptides (peptide-gold-nanoparticle conjugates = Pep-Au-NPs) has proven to be a highly promising tool. The high local peptide concentration surrounding the nanoparticles creates microenvironments in which novel cooperative effects between residues, as well as novel hydrogen bond and charge-relay networks, are generated. As a result, the catalytic efficiency of a peptide can increase by several orders of magnitude, and even generate new catalytic activities and properties, compared to the non-conjugated peptide species. Applying UV/Vis- and fluorescence-based experiments together with suitable kinetic models, enables the characterization and analysis of the kinetic parameters of Pep-Au-NPs.
Our studies provide insight into general properties and possible applications of Pep-Au-NPs for cascade reactions. We highlight the important role the peptide design plays regarding the catalytic activity and substrate specificity of these conjugates, as well as how defined structural changes of the polypeptide chains can be exploited to regulate the catalytic activity of Pep-Au-NPs.
With the obtained knowledge we want to encourage the development of new efficient catalytic systems with beneficial properties and promote the growth of this promising field, which is still in its infancy.
D. J. Mikolajczak, J. L. Heier, B. Schade, B. Koksch, Catalytic Activity of Peptide-Nanoparticle Conjugates Regulated by a Conformational Change. Biomacromolecules 2017, 18, 3557–3562. DOI: 10.1021/acs.biomac.7b00887
D. J. Mikolajczak, B. Koksch, Peptide-Gold Nanoparticle Conjugates as Sequential Cascade Catalysts. ChemCatChem 2018, 10, 4324–4328. https://doi.org/10.1002/cctc.201800961
D. J. Mikolajczak, J. Scholz, B. Koksch, Tuning the Catalytic Activity and Substrate Specificity of Peptide-Nanoparticle Conjugates. ChemCatChem 2018, 10, 5665–5668. https://doi.org/10.1002/cctc.201801521